The demagnetising component of armature reaction in a D.C. generator___________?

Related Mcqs:

1. The e.m.f. induced in the armature of a shunt generator is 600 V. The armature resistance is 0.1 ohm. If the armature current is 200 A, the terminal voltage will be_____________?

   A. 640 V
   B. 620 V
   C. 600 V
   D. 580 V

2. Two generators A and B have 6-poles each. Generator A has wave wound armature while generator B has lap wound armature. The ratio of the induced e.m.f. is generator A and B will be_______________?

   A. 2 : 3
   B. 3 : 1
   C. 3 : 2
   D. 1 : 3

3. Armature reaction of an unsaturated D.C. machine is_____________?

   A. crossmagnetising
   B. demagnetising
   C. magnetising
   D. none of above

4. In a separately excited generator supplying rated load the armature reaction.

   A. is always present
   B. is always absent
   C. may be sometimes present
   D. none of the above

5. Armature reaction in a generator results in_____________?

   A. demagnetisation of leading pole tip and magnetisation of trailing pole tip
   B. demagnetisation of trailing pole tip and magnetisation of leading pole tip
   C. damagnetising the center of all poles
   D. magnetising the center of all poles

6. As a result of armature reaction, the reduction in the total mutual air gap flux in a D.C. generator is approximately______________?

   A. 40 percent
   B. 25 percent
   C. 10 percent
   D. 5 percent

7. The resistance of armature winding depends on

   A. length of conductor
   B. cross-sectional area of the conductor
   C. number of conductors
   D. all of the above

8. Equilizer rings are required in case armature is_______________?

   A. wave wound
   B. lap wound
   C. delta wound
   D. duplex wound

9. The armature core of a D.C. generator is usually made of__________________?

   A. silicon steel
   B. copper
   C. non-ferrous material
   D. cast-iron

10. Open circuited armature coil of a D.C. machine is________________?

    A. identified by the scarring of the commutator segment to which open circuited coil is connected
    B. indicated by a spark completely around the commutator
    C. both A. and (b)
    D. none of the above